In the related art, in a vehicle air conditioner using a cooler cycle, a configuration is known which includes a heater core for circulating cooling water heated by an engine and an evaporator for circulating a refrigerant (for example, refer to PTL 1). In this type of vehicle air conditioner, air circulating in a ventilation duct is heated by the heater core during heating and is cooled by the evaporator during cooling.
In contrast, a vehicle such as an electric vehicle which does not include an engine serving as a vehicle driving source cannot utilize the cooling water of the engine during the heating. Therefore, instead of the above-described cooler cycle, the vehicle employs a vehicle air conditioner utilizing a heat pump cycle. In this type of vehicle air conditioner, flows of the refrigerant are switched so as to perform a switching operation between a cooling mode and a heating mode.
Here, with regard to a vehicle air conditioner in the related art which utilizes the heat pump cycle, the flows of the refrigerant in the cooling mode and the heating mode will be briefly described. FIGS. 5A and 5B are configuration diagrams of the vehicle air conditioner in the related art. FIG. 5A illustrates the heating mode, and FIG. 5B illustrates the cooling mode.
As illustrated in FIG. 5A, in the heating mode, the high-temperature and high-pressure refrigerant which is discharged from a compressor 101 radiates heat in a vehicle compartment condenser 102. Thereafter, the refrigerant is expanded by an expansion valve 104, and is brought into an atomized state with two phases of gas and liquid (rich in a liquid phase). Then, the refrigerant in a vehicle exterior heat exchanger 105 absorbs heat from the vehicle exterior atmosphere. The refrigerant in the atomized state with two phases of gas and liquid (rich in a liquid phase) passes through a heating electromagnetic valve 106 and a junction pipe 107, and flows into a gas-liquid separator 108. Within the refrigerant separated into gas and liquid in the gas-liquid separator 108, the refrigerant in a gas phase is sucked into the compressor 101 again.
Then, air circulated in a ventilation duct 103 by a blower 109 passes through the vehicle compartment condenser 102. In this manner, the air is supplied into a vehicle compartment for the purpose of heating (refer to an arrow in the drawing).
In contrast, in the cooling mode, the high-temperature and high-pressure refrigerant which is discharged from the compressor 101 passes through the vehicle compartment condenser 102 and the expansion valve 104, and heat thereof is radiated to the vehicle exterior atmosphere in the vehicle exterior heat exchanger 105. Thereafter, the refrigerant passes through a check valve 111 and a branch pipe 112, and flows into a cooling electronic expansion valve 113.
Then, the refrigerant is expanded by the cooling electronic expansion valve 113, and is brought into an atomized state with two phases of gas and liquid (rich in a liquid phase). Next, the heat of the refrigerant is absorbed in the evaporator 110, thereby cooling the air inside the ventilation duct 103. Thereafter, the refrigerant with two phases (rich in a gas phase) of gas and liquid which passes through the evaporator 110 passes through the junction pipe 107, and flows into the gas-liquid separator 108. In the refrigerant separated into gas and liquid in the gas-liquid separator 108, the refrigerant in a gas phase is sucked into the compressor 101 again.
Accordingly, the air circulated in the ventilation duct 103 by the blower 109 is cooled by heat absorption in the evaporator 110. Thereafter, the air is circulated by bypassing the vehicle compartment condenser 102. In this manner, the air is supplied into the vehicle compartment for the purpose of cooling.